How can i change my apple icloud email ?

See the article Add and manage email aliases for iCloud Mail on iCloud.com - Apple Support

Note: You can’t delete or turn off a primary iCloud Mail address. You can’t use an alias to create a separate Apple ID, and an email alias can’t be converted to a primary iCloud Mail address.

1. Go to the Apple ID website and sign in.

2. Click the small "Edit" button next to the "Account" section on the website. 

3. At the very top of the account menu, click the hyperlink labelled "Change Apple ID…"

4. Enter the email address that you want to use, then click "Continue."

5. If you changed your Apple ID to a non-Apple address, check that email for a verification code, then enter the code. 

6. Once it's verified, just go to the iCloud website and sign in with your new email address.